Energy & Environmental Materials最新文献

Lithium-ion batteries (LIBs) play a pivotal role in today's society, with widespread applications in portable electronics, electric vehicles, and smart grids. Commercial LIBs predominantly utilize graphite anodes due to their high energy density and cost-effectiveness. Graphite anodes face challenges, however, in extreme safety-demanding situations, such as airplanes and passenger ships. The lithiation of graphite can potentially form lithium dendrites at low temperatures, causing short circuits. Additionally, the dissolution of the solid-electrolyte-interphase on graphite surfaces at high temperatures can lead to intense reactions with the electrolyte, initiating thermal runaway. This review introduces two promising high-safety anode materials, Li₄Ti₅O₁₂ and TiNb₂O₇. Both materials exhibit low tendencies towards lithium dendrite formation and have high onset temperatures for reactions with the electrolyte, resulting in reduced heat generation and significantly lower probabilities of thermal runaway. Li₄Ti₅O₁₂ and TiNb₂O₇ offer enhanced safety characteristics compared to graphite, making them suitable for applications with stringent safety requirements. This review provides a comprehensive overview of Li₄Ti₅O₁₂ and TiNb₂O₇, focusing on their material properties and practical applicability. It aims to contribute to the understanding and development of high-safety anode materials for advanced LIBs, addressing the challenges and opportunities associated with their implementation in real-world applications.

Metal-covalent organic frameworks (MCOF) as a bridge between covalent organic framework (COF) and metal organic framework (MOF) possess the characteristics of open metal sites, structure stability, crystallinity, tunability as well as porosity, but still in its infancy. In this work, a covalent organic framework DT-COF with a keto-enamine structure synthesized from the condensation of 3,3′-dihydroxybiphenyl diamine (DHBD) and triformylphloroglucinol (TFP) was coordinated with Cu²⁺ by a simple post-modification method to a obtain a copper-coordinated metal-covalent organic framework of Cu-DT COF. The isomerization from a keto-enamine structure of DT-COF to a enol-imine structure of Cu-DT COF is induced due to the coordination interaction of Cu²⁺. The structure change of Cu-DT COF induces the change of the electron distribution in the Cu-DT COF, which greatly promotes the activation and deep Li-storage behavior of the COF skeleton. As anode material for lithium-ion batteries (LIBs), Cu-DT COF exhibits greatly improved electrochemical performance, retaining the specific capacities of 760 mAh g⁻¹ after 200 cycles and 505 mAh g⁻¹ after 500 cycles at a current density of 0.5 A g⁻¹. The preliminary lithium storage mechanism studies indicate that Cu²⁺ is also involved in the lithium storage process. A possible mechanism for Cu-DT COF was proposed on the basis of FT-IR, XPS, EPR characterization and electrochemical analysis. This work enlightens a novel strategy to improve the energy storage performance of COF and promotes the application of COF and MCOF in LIBs.

Hydrogen spillover effect has recently garnered a lot of attention in the field of electrocatalytic hydrogen evolution reactions. A new avenue for understanding the dynamic behavior of atomic migration in which hydrogen atoms moving on a catalyst surface was opened up by the setup of the word “hydrogen spillover.” However, there is currently a dearth of thorough knowledge regarding the hydrogen spillover effect. Currently, the advancement of sophisticated characterization procedures offers progressively useful information to enhance our grasp of the hydrogen spillover effect. The understanding of material fabrication for hydrogen spillover effect has erupted. Considering these factors, we made an effort to review most of the articles published on the hydrogen spillover effect and carefully analyzed the aspect of material fabrication. All of our attention has been directed toward the molecular pathway that leads to improve hydrogen evolution reactions performance. In addition, we have attempted to elucidate the spillover paths through the utilization of DFT calculations. Furthermore, we provide some preliminary research suggestions and highlight the opportunities and obstacles that are still to be confronted in this study area.

Electrocatalytic reduction of CO₂ into high energy-density fuels and value-added chemicals under mild conditions can promote the sustainable cycle of carbon and decrease current energy and environmental problems. Constructing electrocatalyst with high activity, selectivity, stability, and low cost is really matter to realize industrial application of electrocatalytic CO₂ reduction (ECR). Metal–nitrogen–carbon (M–N–C), especially Ni–N–C, display excellent performance, such as nearly 100% CO selectivity, high current density, outstanding tolerance, etc., which is considered to possess broad application prospects. Based on the current research status, starting from the mechanism of ECR and the existence form of Ni active species, the latest research progress of Ni–N–C electrocatalysts in CO₂ electroreduction is systematically summarized. An overview is emphatically interpreted on the regulatory strategies for activity optimization over Ni–N–C, including N coordination modulation, vacancy defects construction, morphology design, surface modification, heteroatom activation, and bimetallic cooperation. Finally, some urgent problems and future prospects on designing Ni–N–C catalysts for ECR are discussed. This review aims to provide the guidance for the design and development of Ni–N–C catalysts with practical application.